Compositions based on random propylene copolymers, process for their manufacture, and heat-sealable multilayer sheets comprising them
View Patent ↗Compositions based on propylene polymers (compositions (C)) comprising: a) from 61 to 74% by weight of a random propylene copolymer (copolymer (A)) comprising from 8 to 16% by weight of monomer units derived from 1-butene and less than 0.5% by weight of monomer units derived from ethylene, and b) from 39 to 26% by weight of a random propylene copolymer (copolymer (B)) comprising from 35 to 50% by weight of monomer units derived from 1-butene and from 0 to 1% by weight of monomer units derived from ethylene. Process for the manufacture of these compositions.
1. A composition based on propylene polymers having a melting temperature of 125 to 146° C. and a sealing temperature below 100° C. comprising:
from 61 to 74% by weight of a random propylene copolymer (copolymer (A)) comprising from 8 to 16% by weight of monomer units derived from 1-butene without monomer units derived from ethylene, and
from 39 to 26% by weight of a random propylene copolymer (copolymer (B)) comprising from 35 to 50% by weight of monomer units derived from 1-butene without monomer units derived from ethylene.
2. A composition according to claim 1 , having a melting temperature of 128 to 138° C. and a sealing temperature below 98° C., comprising:
from 62 to 72% by weight of a propylene/1-butene copolymer (A) essentially comprising from 86 to 90% by weight of monomer units derived from propylene and from 10 to 14% by weight of monomer units derived from 1-butene, and
from 38 to 28% by weight of a random propylene copolymer (B) comprising from 38 to 45% by weight of monomer units derived from 1-butene without monomer units derived from ethylene.
3. A composition according to claim 1 exibiting a melt flow index (MFI) measured according to Standard ASTM D1238 (230° C.; load: 2.16 kg), of 1 to 15 g/10 min.
4. A composition according to claim 1 exibiting a sealing temperature of at most 90° C.
5. A composition according to claim 1 characterized in that the melting temperature is at least 35° C. greater that the sealing temperature.
6. A composition according to claim 1 exibiting a melting peak MT3 of 50 to 90° C.
7. A composition according to claim 2 exibiting a melt flow index (MFI) measured according to Standard ASTM D1238 (230° C.; load: 2.16 kg), of 1 to 15 g/ 10 min.
8. A composition according to claim 2 exibiting a sealing temperature of at most 90° C.
9. A composition according to claim 2 characterized in that the melting temperature is at least 26° C. greater that the sealing temperature.
10. A composition according to claim 2 exibiting a melting peak MT3 of 50 to 90° C.
11. A composition according to claim 3 exibiting a sealing temperature of at most 90° C.
12. A composition according to claim 3 characterized in that the melting temperature is at least 35° C. greater that the sealing temperature.
13. A composition according to claim 3 exibiting a melting peak MT3 of 50 to 90° C.
14. A composition according to claim 4 characterized in that the melting temperature is at least 26° C. greater that the sealing temperature.
15. A composition according to claim 4 exibiting a melting peak MT3 of 50 to 90° C.
16. A composition according to claim 5 exibiting a melting peak MT3 of 50 to 90° C.
17. A process for the manufacture of a propylene polymer composition having a melting temperature of 125 to 146° C. and a sealing temperature below 100° C. comprising mechanical melt blending
from 61 to 74% by weight of a random propylene copolymer (copolymer (A)) comprising from 8 to 16% by weight of monomer units derived from 1-butene without monomer units derived from ethylene, and
from 39 to 26% by weight of a random propylene copolymer (copolymer (B)) comprising from 35 to 50% by weight of monomer units derived from 1-butene without monomer units derived from ethylene
in an internal or external mixer.
18. A process for the manufacture of a propylene polymer composition having a melting temperature of 125 to 146° C. and a sealing temperature below 100° C. comprising copolymerizing
from 61 to 74% by weight of a random propylene copolymer (copolymer (A)) comprising from 8 to 16% by weight of monomer units derived from 1-butene without monomer units derived from ethylene in a first stage, and
from 39 to 26% by weight of a random propylene copolymer (copolymer (B)) comprising from 35 to 50% by weight of monomer units derived from 1-butene without monomer units derived from ethylene
wherein copolymer B is synthesized in a second stage in the presence of copolymer (A).
19. A heat-sealable multilayer sheet, characterized as comprising at least one sealing layer composed substantially of a propylene polymer composition having a melting temperature of 125 to 146° C. and a sealing temperature below 100° C. comprising:
from 61 to 74% by weight of a random propylene copolymer (copolymer (A)) comprising from 8 to 16% by weight of monomer units derived from 1-butene without monomer units derived from ethylene, and
from 39 to 26% by weight of a random propylene copolymer (copolymer (B)) comprising from 35 to 50% by weight of monomer units derived from 1-butene without monomer units derived from ethylene.
20. A packaging material characterized as comprising a heat-sealable multilayer sheet further characterized in that the sheets comprise at least one sealing layer composed substantially of a propylene polymer composition having a melting temperature of 125 to 146° C. and a sealing temperature below 100° C. comprising:
from 61 to 74% by weight of a random propylene copolymer (copolymer (A)) comprising from 8 to 16% by weight of monomer units derived from 1-butene without monomer units derived from ethylene, and
from 39 to 26% by weight of a random propylene copolymer (copolymer (B)) comprising from 35 to 50% by weight of monomer units derived from 1-butene without monomer units derived from ethylene.